Arrangement for distributing oil in a camshaft

ABSTRACT

An arrangement for distributing oil in a camshaft of an internal-combustion engine comprises a cylindrical insert which extends axially in the camshaft and carries two separate oil flows in the camshaft. The insert has a centrally arranged oil duct for one oil flow and a hollow space for another oil flow which is constructed between the insert and the camshaft and forms a portion of the arrangement. Both oil flows are fed to the camshaft or discharged from it by way of radial ducts.

The invention relates to an arrangement according to the preamble ofclaim 1.

From the FR-A-54 29 94, an arrangement for distributing oil in acamshaft of an internal-combustion engine is known in which the bearingpoints for the camshaft are connected to an oil circulating system and acylindrical insert extends axially inside the camshaft and bounds ahollow space between the camshaft and this insert and has a centrallyextending oil duct.

By means of this arrangement, one and the same oil flow can be guidedinside the oil duct to remote lubricating points and can be guidedinside the hollow space to close lubricating points.

The invention is based on the object of providing an arrangement for thedistribution of oil in a camshaft which makes it possible to guideseveral oil flows in the camshaft independently of one another.

This object is achieved by means of the characteristics of claim 1.Advantageous developments of the invention are indicated in thesubclaims.

This arrangement for the distribution of oil permits the targetedguiding of a first and a second oil flow inside a camshaft. In thiscase, the oil flows are completely separated from one another and maytherefore have different pressures, flow rates, flow directions, etc.

The oil duct, which is arranged centrally in the insert, by way of afirst radially extending duct, is connected to the oil circulatingsystem and carries a first oil flow, for example, from one end to thecamshaft to one or to several bearing points. The oil duct is coaxiallyenclosed at least in sections by a circular hollow space which extendsbetween the insert and the camshaft. In this hollow space, a second oilflow is carried which is connected to the oil circulating system by wayof a second duct.

Between a first and a second duct, the insert has a first sealingsection which axially bounds the hollow space on one side and separatesthe oil flows from one another.

Advantageously, the arrangement is suitable for various applications.Thus, for example, from one end of the camshaft, two oil flows may befed into the oil duct or the hollow space in order to ensure, by way ofthe first duct, the lubricating of bearing points while, by means of thesecond duct, hydraulically connectable and disconnectable cams areoperated.

In a further application, the arrangement may be used for actuating ahydraulically operated phase converter. In this case, the phaseconverter changes the relative rotating position between the inletcamshaft and the outlet camshaft of an internal-combustion engine bymeans of an axial displacement of a control piston in two end positions.According to the displacement direction of the control piston, apressurized-oil flow is fed through one of the ducts into the camshaft,while the unpressurized oil volume displaced by the control piston isdischarged by way of the second duct.

The insert may be made of plastic to be light in weight, cost-saving andinsensitive to tolerances. It is pressed into the camshaft with a slightoverdimension.

For avoiding transversal vibrations of the insert in the camshaft, it isprovided in the area of the hollow space with ribs which are arrangedbetween the oil duct and the inner surface of the camshaft and whichdivide the hollow space into several oil grooves.

The first sealing section consists of several radially acting sealingelements which effectively separate the oil flows from one another andprevent vibrations of the insert in this area.

An embodiment of the invention is explained in detail by means offigures.

FIG. 1 is a partial sectional view of an arrangement;

FIG. 2 is an enlarged sectional view along Line II--II according to FIG.1;

FIG. 3 is an enlarged view of a second embodiment of a detail Xaccording to FIG. 1;

FIG. 4 is an enlarged view of a third embodiment of a detail X accordingto FIG. 1;

FIG. 5 is an enlarged view of a detail Y according to FIG. 1; and

FIG. 6 is an enlarged view of a detail Z according to FIG. 1.

A hollow constructed camshaft 1 of an internal-combustion engine, whichis not shown, has cams 2 for the operating of lift valves, which arealso not shown, and is held in several bearing points 3. Along a sectionE, inside the camshaft 1, an axially extending insert 4 is provided inwhich a centrally extending oil duct 5 is arranged which extends from anopen end 6 of the camshaft 1 to close to the opposite end of section E.

From the end 6, the oil duct 5 is coaxially surrounded along a section Hby a hollow space 7 which is constructed between the oil duct 5 and theinner surface 8 of the camshaft 1.

In a section D, which remains between section E and section H, theinsert 4 has a first sealing section 9 which consists of several axiallyspaced, radially acting sealing elements 10.

By way of a radially extending first duct 15, the oil duct 5 isconnected with a first bearing point 3 which is connected to an oilcirculating system of the internal-combustion engine which is not shown.

By way of a radially extending second duct 16, the hollow space 7 isconnected adjacent to the sealing section 9 with a second bearing point3a which is also connected to the oil circulating system.

On the end 17, which is situated opposite the end 6, the insert 4 has acover 18 which closes off the oil duct 5 and which, together with theadjacent portion of the insert 4, forms a second sealing section 19.Adjacent to the first duct 15, the sealing sections 9 and 19 aredesigned such that a ring gap 20 which encloses the oil duct 5 coaxiallyremains between them and the inner surface 8.

Along section H, ribs 21 are arranged which project radially from theoil duct 5 and support the insert 4 in the area of the hollow space 7with respect to the surface 8 and thus prevent vibrations of the insert4 in the camshaft 1.

According to FIG. 2, the ribs 21 divide the hollow space 7 into axiallyextending oil grooves 22. Adjacent to the second duct 16, the firstsealing section 9 and the hollow space 7 are designed such that anotherring gap 20 remains between them and the inner surface 8 and coaxiallyencloses the oil duct 5.

On the front end 6 of the camshaft 1, a bushing 23 is pressed in in anoiltight manner which accommodates the oil duct 5 and bounds the hollowspace 7 in such a manner that the oil flowing in it arrives from a bore24 of the camshaft 1 according to FIG. 6 in a phase converter 25 whichis not shown in detail.

According to FIG. 1, the sealing elements 10 of the sealing section 9are constructed in the manner of a truncated cone but, according to asecond embodiment (FIG. 3), may also be constructed of cylindrical rings30 or may, according to a third embodiment (FIG. 4), be shaped in themanner of a bead. In all embodiments, the sealing element 10 which isadjacent to the second duct 16 has a cylindrical design.

The second sealing section 19 and the portion of the oil duct 5 disposedin the bushing 23 have surrounding sealing lips 31.

In a simple manner, the insert 4 may be manufactured from a filledplastic material, such as PA66 GF35, in which case the cover 18 ismounted by means of ultrasonic welding.

During the mounting, the complete insert 4 is slid into the camshaft 1in such a manner that the oil duct 5, on its end 6, closes off flushwith the camshaft 1; then the bushing 23 is pressed in.

During the operation of an internal-combustion engine equipped with thearrangement, pressurized oil is fed into the ring duct 20 by way of abore 32 in the camshaft 1 which forms a portion of the first duct 15,which pressurized oil arrives in the phase converter 25 through the oilduct 5. From an oil circulating system, this oil is fed to theinternal-combustion engine by way of the first bearing point 3. In thiscase, unpressurized oil is carried from the phase converter 25 by way ofthe bore 24 into the oil grooves 22 and is returned into the oilcirculating system by way of the second duct 16 and the second bearingpoint 3.

When the phase converter is actuated again, the pressurized oil isguided by way of the second bearing point 3 into the oil grooves 22; theunpressurized oil flows in the oil duct 5 from the phase converter 25 tothe first bearing point 3.

What is claimed is:
 1. An arrangement for distributing oil in aninternal-combustion engine camshaft (1), comprising bearing points (3,3a) for the camshaft (1) connected to an oil circulating system and acylindrical insert (4) extending axially within the camshaft (1),bounding a hollow space (7) between the camshaft (1) and the insert (4)and having a centrally extending oil duct (5), wherein the oil duct (5)is arranged to carry a first oil flow and is connected, via a first duct(15) in a first (3) of the bearing points (3, 3a) with the oilcirculating system, the insert (4) is coaxially surrounded at least insections by the hollow space (7) arranged to carry a second oil flow andconnected, via a second duct (16), to the oil circulating system, andthe insert (7), between the first duct (15) and second duct (16), has asealing section (9) which axially bounds the hollow space (7), actsradially and is provided with several axially spaced sealing elements(10), the insert (4) having on each side of the sealing section (9) onering gap (20) which coaxially encloses the oil duct (5) adjacent to thefirst and second ducts (15, 16) and the second duct (16) is connectedwith the oil circulating system via a second of the bearing points (3a).2. The arrangement according to claim 1, wherein the insert (4), in thearea of the hollow space (7), has radially projecting ribs (21)supporting the insert (4) in the camshaft (1).
 3. The arrangementaccording to claim 1, wherein the insert (4), adjacent first duct (15),has a second radially acting sealing section (19).